To specify whether the Application Server tries to reconnect to the primary
broker when the connection is lost, select the Reconnect checkbox. If enabled and
the primary broker goes down, Application Server tries to reconnect to another broker in
the JMS Hosts list.

When Reconnect is enabled, also specify the following attributes:

Address List Behavior: whether
connection attempts are in the order of addresses in the JMS Hosts List (priority)
or random order (random). If set to Priority, Java Message Service tries to connect
to the first MQ broker specified in the JMS Hosts list and uses another one only if
the first broker is not available. If set to Random, Java Message Service selects
the MQ broker randomly from the JMS Hosts list. If there are many clients attempting
a connection using the same connection factory, use this setting to prevent them from
all attempting to connect to the same address.

Address List Iterations: number
of times the Java Message Service iterates through the JMS Hosts List in an effort
to establish (or re-establish) a connection). A value of -1 indicates that the number
of attempts is unlimited.

Reconnect Attempts: the number
of attempts to connect (or reconnect) for each address in the JMS hosts list before
the client runtime tries the next address in the list. A value of -1 indicates that
the number of reconnect attempts is unlimited (the client runtime attempts to connect
to the first address until it succeeds).

Reconnect Interval: number of seconds
between reconnect attempts. This applies for attempts on each address in the JMS hosts
list and for successive addresses in the list. If it is too short, this time interval
does not give a broker time to recover. If it is too long, the reconnect might represent
an unacceptable delay.

Load-Balanced Message Inflow

Application Server delivers messages randomly to MDBs having same ClientID . The ClientID is required for durable subscribers.

For non-durable subscribers in which the ClientID is not
configured, all instances of a specific MDB that subscribe to same topic are considered
equal. When an MDB is deployed to multiple instances of the Application Server, only one
of the MDBs receives the message. If multiple distinct MDBs subscribe to same topic,
one instance of each MDB receives a copy of the message.

To support multiple consumers using the same queue, set the maxNumActiveConsumers property of the physical destination to a large value. If this property
is set, MQ allows up to that number of MDBs to consume messages from same queue. The
message is delivered randomly to the MDBs. If maxNumActiveConsumers is
set to -1, there is no limit to the number of consumers.